1. Field of the Invention
The present invention relates to an engraving sheet having a support layer and an engraving layer formed on the support layer with the engraving layer to be engraved in accordance with a desired pattern, a photograph of the face of an individual or the like down to a depth to the support layer, and a method of engraving the engraving sheet.
2. Description of the Related Art
In known anti-counterfeit techniques, an image is engraved on an identification card, a passport, a bank book, or a plastic sheet of a variety of cards for identification, and a reflected light bearing the image is checked to see if it is a genuine engraved image. However, the determination method dependent on the reflected light only needs a complicated technique. Japanese Unexamined Patent Application Publication No. 6-15794 discloses an engraving sheet that is formed of a support layer and an engraving layer formed on the support layer with the engraving sheet to be engraved deep into the support layer to form a water mark.
A reverse image under the presence of transmitted light rays entering from behind is recognized as an engraved picture to determine authenticity of the image. The reflected light image, typically distinctly formed, is easy to transfer. To be applied as a certificate, the engraved image has much room for improvement from the following points. Namely, the engraved image needs to be difficult to counterfeit, and needs to be durable, and elastic much like paper, and excellent as an image, and presents no environmental problems when it is burned in a disposal process.